| Distributed antenna systems (DASs) have been shown to improve the coverage and increase the capacity in cellular networks by reducing the access distance to user terminals (UTs) and by attaining macrodiversity gains. However, the conventional DASs do not inherently mitigate inter-cell interference. In this thesis, coordinated multi-point transmission schemes are developed for interference mitigation in the downlink of a cellular DAS.;In the second part, the joint selection of the ports and the corresponding beam steering coefficients that maximize the minimum signal-to-interference-plus-noise ratio of the UTs in a coordinated multi-cell DAS, in which the transmit power of each port is fixed, is considered. This problem is NP-hard. To circumvent this difficulty, a two-stage polynomial-complexity technique that relies on semidefinite relaxation and Gaussian randomization is developed. The performance of the proposed technique is shown to be comparable to that of exhaustive search. Additionally, it is demonstrated that proper port selection yields significant power savings in the cellular network.;The thesis is comprised of two parts. In the first part, two precoding schemes are developed, which enable coordinated transmission from multiple distributed antenna ports in a cellular DAS with a total power constraint. The goal is to serve multiple UTs in a particular resource block in each cell, while mitigating intra-cell and inter-cell interference. Simulation is used to show the performance gains attained by the proposed DAS schemes as compared to their co-located antenna system counterparts, and by centralized multi-cell processing as compared to single-cell processing. |
